Various methods and apparatus have long been used for positioning, stabilizing and supporting bone segments to repair bone fractures in humans and animals. Simple external apparatus such as slings and splints are well known and are still used alone or in combination with invasive apparatus to repair broken bones. Slings are used alone in certain circumstances where use of invasive apparatus or implants presents an unacceptable risk of injury to a patient. For example, slings are often used without any invasive apparatus to repair a fractured clavicle because implantation of known invasive bone repair apparatus to repair a fractured clavicle can risk life threatening damage to the patient's subclavian artery or damage to other vessels, nerves, nerve bundles, vital organs or surrounding tissues.
Since invasive repair of a fractured clavicle presents medical risk, patients having a fractured clavicle often forgo the benefits offered by various invasive apparatus and implants. Such benefits which include improved bone segment positioning, stabilizing and support promote more rapid recovery and reduce patient discomfort. Further, use of slings alone often allows misaligned bone segments to heal such that a visibly conspicuous deformation or a weak area remains which is susceptible to re-injury. Accordingly, it would be advantageous to provide a clavicle repair apparatus with reduced risk of injury to the patient.
Known invasive apparatus for bone segment repair include various configurations of bone fracture reduction rods, orthopedic screws, intramedullary nails, intramedullary screws and the like. For example, U.S. Pat. No. 6,338,732 to Yang discloses an in-marrow nail structure having two threaded ends for drilling and engaging fractured bone segments. A nut is screwed over a threaded proximal portion of the structure to apply compressive force to the bone segments. The apparatus disclosed in Yang and similar devices involve installing a drilling tip within the intramedullary cavity. These devices typically incorporate threads having a cutting edge in at least a distal portion whereby drilling is performed by rotating the devices around their longitudinal axis. Accordingly, such devices are typically unsuitable for implantation in curved bone segments. Such devices also present a high risk of drilling through a bone segment into surrounding tissue, and are therefore not well suited for use in repairing a fractured clavicle. It would be desirable to provide an intramedullary apparatus that is suitable for use in curved bone segments without presenting a high risk of damaging surrounding tissue.
In addition to providing a drilling capability for implanting an intramedullary device, the threaded distal portion of some known devices serves as an anchor which secures the distal portion of the device to a distal bone segment. Bone segments are held together by also providing a compressing portion which engages the proximal bone segment and travels toward the anchored distal portion.
In another type of known intramedullary support apparatus, an expandable anchor portion is provided for engaging the distal bone segment. For example, U.S. Pat. Nos. 3,779,239; 3,760,802 and 4,227,518 disclose particular intramedullary retraction nails that include an expansion element in their distal portion. The expansion elements serves as an anchor in a distal bone segment. The aforementioned devices are generally directed toward a rod disposed with a tubular portion. Relative linear motion between the rod and the tubular portion, such as by threading the rod to the tubular portion, causes actuation of the expansion element to engage the bone lining in the distal portion. A bolt head and or nut and washer are installed over or incorporated with the proximal portion of the rod which protrudes from a hole drilled in the proximal bone segment. In the apparatus disclosed in U.S. Pat. Nos. 3,779,239 and 3,760,802 the central rod is curved to correspond with the curvature of the bone under repair.
Installation of a rod within the intramedullary cavity can increase the risk of damage to the bone lining, and can be difficult to perform on curved bones such as the clavicle. Furthermore, apparatus heretofore known that are adapted for providing a distal anchor portion are not adapted for aligning a displaced fracture. Insertion of such devices to a misaligned fracture can cause increased separation of bone segments and possibly damage surrounding tissue. The rod's rigidity can also prevent it from centering radially when the expandable anchor portion is deployed. Such devices can therefore allow a bone to heal in a misaligned or overlapped state which can be weak or appear deformed. It would therefore be desirable to provide a intramedullary support device for use on curved bone segments that does not include a rigid internal rod portion, and which is self centering and adapted to align bone segments at a displaced fracture site.
Known IM fixation devices having an expandable anchor portion are typically constructed with a number of separate moving components. The number of moving components can make such devices expensive and susceptible to malfunction. It would be desirable to provide an IM fixation device having an expandable anchor portion which does not require a large number of separate components.
The proximal portion of known IM fixation devices is often movably disposed within the IM region of the proximal portion of a fractured clavicle bone. Such proximal portions of the device protrude from the posterior lateral end of the clavicle bone. A stabilizing nut is typically rotated to engage the threaded portion of the IM fixation device, thus causing the stabilizing nut to partially traverse the threaded portion of the IM fixation device. As the stabilizing nut traverses the threaded portion, the stabilizing nut pushes the proximal portion of the fractured clavicle bone toward the distal portion of the fractured clavicle bone. The stabilizing nut is rotated until the distal and proximal portions of the fractured clavicle bone contact each other, such that the fractured ends of the clavicle bone remain in contact with each other to allow for the accelerated healing of the clavicle fracture.
Several heretofore known IM fixation devices include portions that prominently protrude from the proximal lateral end of the clavicle bone. Even small movement of such devices can causes extreme pain to a patient. It would therefore be desirable to provide an intramedullary fixation device that does not prominently protrude externally from the bone.
Installation of some known intramedullary support devices involves invasive surgery wherein a cut-down must be performed at the fracture site. Such surgical installations increase the risk of infection, lengthen the recovery period, and often leave large unsightly scars. It would therefore be desirable to provide a method and apparatus for repairing fractured bones which is minimally invasive and which does not require a surgical cut-down at the fracture site.
Many known intramedullary support devices are not fixed within the intramedullary space and can therefore suffer from migration within the intramedullary space. It has been known for intramedullary devices or components thereof to migrate such that they pierce a patient's surrounding tissue, skin, or vital organs. It would therefore be desirable to provide an intramedullary support device that does not suffer from migration.
Many heretofore known intramedullary fixation devices are difficult to remove after a patient's fractured bone has healed. It would therefore be desirable to provide an intramedullary support device that is more easily removed from the bone after a fracture has healed.